1998 Winnebago Chieftain WFL34WY engine charges the chassis battery but not house batteries

1998 Winnebago Chieftain WFL34WY Chevy P30 chassis the engine charges the chassis battery and the generator charges the house batteries. My research says the engine should also charge the house batteries? I can't find a wiring diagram that clearly shows the wiring from the batteries, battery disconnect, relay etc. Can someone please help?


Mornin Cowboy, In order for the engines alternator to charge the house batteries there MUST be a connection (when engine is running) between the two WELL DUH YOU SAY..

On many RV's that's made possible by use of a mechanical 100% duty cycle high current relay that closes to in effect connect the house battery and engine battery/alternator ONLY WHEN THE ENGINE IS STARTED (or key switch function) but opens otherwise so house battery use doesn't discharge the engine battery and leave you stranded. These relays that appear similar to the old Ford starter solenoids (two big side posts and two small terminals) can be found or traced by big cables on or near the engine battery (plus smaller wires to the two activation terminals) which connect to it and the relay and then lead back to the house battery with a big cable.

NOTE if that solenoid doesn't get the small wire activation signal voltage it doesn't close in which case the engine running cant charge the house battery. Its not too hard to troubleshoot that system, when the engine is started (or key switch activation) there should be an activation signal voltage to the relay (small terminals) to close it so the batteries are effectively connected together. That Normally Open relay should be OPEN when engine isn't running yet has to close to charge the house battery...……..

NOTE some RV's have a manual emergency push switch so you can engage it and that closes the relay in addition to the normal automatic activation upon the engine running or key switch activated.

On others a sold state (containing diodes, an isolator) device is used so alternator current can feed into and charge the house battery yet house battery use cant discharge the engine battery. They have big terminals with a cable to the engine battery and another back to the house battery.

BOTTOM LINE look for a mechanical relay or a solid stage charge isolator that connects with big cables to the engine battery and troubleshoot it. If its mechanical it cant close unless its small activation terminals receive signal voltage (automatic when engine runs or manual push switch activated), if its a solid state charge Isolator it wires to engine and house batteries and alternator.

Ive also found a loose or resistive or even full open connection in the wiring back to your house battery is the problem. Look at your house battery for wiring from it to the engine?? Maybe there's a blown fuse or tripped breaker or an open wire or connection at EITHER the house or engine side of the charge circuit. Check all the fuses and/or breakers in the charge circuit !!!!!!!!!!!!

NOTE the extent and current to which that system can charge the house battery when running depends on the cable size and distance and engines voltage regulation system and other factors and often it may not take the house batteries to full 100% SOC as well as a smart charger but still "works"

You gotta find the big cables on your engine battery that wire to a relay or sold state charge isolator and back to the house battery and insure its wired right and actually working. I've had many mechanical relays that didn't work because they didn't receive the activation signal voltage or there was a bad connection or bad wire. Ive had less sold state charge isolators go bad. FIND THE RELAY OR DEVICE AND TROUBLESHOOT IT. Turn on the engine key and listen for a relay click/closure under the hood??? See if you have an emergency push switch that makes a relay click/close under the hood???

Do you know if your RV even has a system to charge the house battery via the alternator???????????? it may not. How are you monitoring what charge if any (when driving) and the charge state of your house battery?? I have a digital voltmeter on my house battery bank visible when I'm driving and I see what's happening. If there are long runs of too small wire from the engines system back to the house battery it doesn't receive a lot of charge current.

PS maybe one of the fine gents here can post a picture of the relay or solid state charge isolator so you know what to look for. They are typically under the hood often near the engine battery and have big cables wired to it. Its easy to jump 12 volts to a relay to see if its closing and/or listen to it when someone turns the engine key to see if its activated and closes.

John T
Cowboy, here's a PDF containing technical info about your motorhome, it may or may not help look it over. Do you know if your motorhome even has a charge house battery via the engine alternator function??? If not they aren't all that hard to install. I have seen them (when a used RV dealer) with the relay or solid state isolator and some ONLY a switch and wire between the house and engine battery...


John T